The present invention relates to a metal gasket with low heat transmission. In particular, heat transmission between engine parts is reduced by the gasket of the invention.
A metal gasket, such as a steel laminate gasket, has been known and used for sealing between engine parts, such as between a cylinder block and a cylinder head and between a cylinder head and an exhaust manifold.
The steel laminate gasket comprises at least two metal plates and sealing devices, such as beads, formed around holes to be sealed. One or more metal plate may be installed between the metal plates. When the steel laminate gasket is tightened, the beads are compressed and all the plates substantially abut against each other without space therebetween.
Accordingly, although the steel laminate gasket can securely seal between the engine parts, heat between the engine parts is substantially completely transmitted through the gasket.
In an engine equipped with an inlet manifold, pressure and temperature applied to the inlet manifold are relatively low when comparing with those applied to an exhaust manifold. Therefore, a conventional gasket made of asbestos, glass fibers, carbon fibers or other gasket materials has been used as an inlet manifold gasket.
Recently, an engine is required to provide high power in small size. Temperature in the new engine becomes high when operated, but heat does not generally affect engine parts while the engine is operated because the engine is cooled. However, when the engine is stopped, heat by the engine affects the engine parts, such as the inlet manifold, and may cause trouble in starting an engine with a fuel injection system, which is attached to the inlet manifold.
Namely, in case a car is stopped for a while to allow the engine to cool down, heat by the engine does not affect the fuel injection system attached to the inlet manifold. However, in case a car is started within a short period of time after the car was stopped, heat from the cylinder head is transferred to the inlet manifold through a gasket and causes vapor lock at the fuel injection system. Namely, the engine may not be started until the engine is cooled.
In order to reduce heat transmission from the engine to the inlet manifold, a gasket with heat insulating characteristics is required. The conventional gasket made of asbestos or a conventional gasket material is low in heat transmission, but such material is not good as a gasket with heat insulating characteristics.
A conventional steel laminate gasket has high heat transmission characteristics, but heat is transmitted instantly from the cylinder head to the inlet manifold through the steel laminate gasket. Therefore, the conventional steel laminate gasket can not be used as a gasket for the inlet manifold.
Accordingly, one object of the present invention is to provide a metal gasket, which can reduce heat transmission between two engine parts.
Another object of the invention is to provide a metal gasket as stated above, which can radiate heat from the engine parts.
A further object of the invention is to provide a metal gasket as stated above, wherein two engine parts can be sealed effectively.
A still further object of the invention is to provide a metal gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.